1. Field of the Invention
In certain applications where strip material is included it be required that the strip material is provided with a lining on one or on both sides which is normally thin in relation to the thickness of the strip material. The application of these linings often takes place in special coating machines, the configuration of which is determined by what kind of strip is to be coated and by the consistence and shape of the strip. The present invention comprises a method and a device for coating of strip where the coating machine comprises, inter alia, a strip wind-off reel for the non-coated strip, and a wind-up reel for the coated strip as well as a number of intermediate rolls.
2. The Prior Art
The manufacture of strip is performed in special strip rolling mills, foil mills, paper and cardboard manufacturing machines, etc., which are designed based on the material properties of the strip, the width, the thickness, the winding speed, etc. Characteristic of most of the strip-manufacturing tools and machines is, however, that the finished strip is led to a wind-up reel where the strip is wound up into a coil.
The linings with which strip in certain applications, or for various reasons, has to be provided may have different insulating, sealing or protective functions. During cold rolling of strip, for example, a thin layer of paper is placed on one side of the strip before the winding up starts in order to protect the strip against scratches or other damage. Within the packing industry it is very common to coat both aluminum foil and thick paper with a plastic lining for example for use as packaging for soft drinks, milk, etc. In this connection, linings may either be positioned loosely on the strip or be more or less secured to the strip in question.
There are also applications where it is desirable for the width of the linings to be wider than the strip, that is, the side edges of the linings shall extend outside the edges of the strip. In such applications, it is also common for linings to be applied on both sides of the strip. A method and a device according to the invention may be used in coating machines with linings on either one or or both of the sides of the strip and where the linings are wider than the strip to be coated and where the linings are made from coating strips in the form of coils placed on coating strip wind-off reels between the strip wind-off reel of the coating machine and the wind-up reel.
In connection with the above-mentioned coating, problems of various kinds arise. To explain why the problems arise, a short and schematic description will first be given of a coating method with a coating machine which applies linings on both sides of the strip. In addition to the above-mentioned strip wind-off reel, wind-up reel, intermediate rolls and coating strip wind-off reels, such a coating machine also comprises two deflector rolls.
After the coil with the strip to be coated has been placed on the strip wind-off reel, the strip is passed over the intermediate rolls to the wind-up reel. The coating strips, which arrive from respective wind-off reels placed on respective sides of the strip, are each pressed against a respective side of the strip via the above-mentioned deflector rolls. After the deflector rolls, thus, both linings and strip will be passed over the following rolls. Upon passage over these rolls, depending on the direction of rotation of the rolls, first one of the linings and then the other lining will make contact with the periphery of some roll. Because of the stresses which then arise in the linings, undesired formation of wrinkles may arise in the linings. Swedish patent publication number 466 742 describes one method which, with the aid of a roll filling strip, prevents the occurrence of these wrinkles.
To obtain as homogeneous and compact a coil as possible, it is necessary that the space which is formed outside the strip and between the linings of the finished coil be filled in some way. This is suitably done by the introduction of so-called edge filling strip. This is made of strips of thin paper or similar material which are narrow in relation to the strip. To adapt to the thickness of the strip, it may be necessary for the edge filling strip to consist of strips positioned one above the other. In the same way as the strip and the linings, the strips of paper or similar material are also wound in the form of coils on wind-off reels. However, it has proved relatively difficult to insert the edge strips between the two linings and to cause the edge strips to be positioned such that, during the coating process and in an as-wound coil, they have a plane and straight orientation in relation to both the strip and the outer edges of the linings.